Purpose :
Although advanced glycation end products (AGEs) have been reported to increase in the retina with age and in diabetes, and to cause pathological changes, data is not available for quantitative changes in AGEs at the vitreoretinal interface or in the inner limiting membrane (ILM). We therefore analyzed AGEs in ILMs removed during vitreous surgery for retinal diseases.

Methods :
We collected ILMs from 34 eyes from 31 patients undergoing vitrectomy, during which Coomassie brilliant blue G was used to visualize the ILM before peeling. The ILM fragments were hydrolyzed with 6N hydrochloric acid at 110 °C for 20 h. We then dehydrated the extracts, re-dissolved them in distilled water, and quantified the AGE, Nε-(Carboxymethyl)lysine (CML), and seven amino acids (Phe, Ala, Tyr, Var, Leu, Arg, and Lys) in the extracts using liquid chromatography-tandem mass spectrometry (3200QTRAP; AB Sciex, Concord, Canada). The CML content of ILMs was normalized to their amino acid content.

Results :
The patients had a mean age of 68.9 ± 7.6 y and 19 eyes were from women. The primary retinal diseases for which vitrectomies were performed were epiretinal membranes (ERM, 19 eyes), diabetic macular edema (DME, 6 eyes), proliferative diabetic retinopathy (PDR, 5 eyes), and macular holes (MH, 4 eyes). 17 eyes were from patients with a medical history of diabetes. The mean (± SD) CML content was 0.29 ± 0.24 nM/nM amino acids, with a range of 0.07 – 1.02 nM/nM amino acids. We found no significant correlation between CML content and age (p = 0.39, Pearson's product-moment correlation coefficient). However, CML levels were significantly higher in diabetic patients than nondiabetic patients (p = 0.02, Student t-test). When we compared CML levels from the nondiabetic patients, who had been treated for ERMs or MHs, with DME patients we found no significant difference, but CML levels were significantly higher in PDR patients (p < 0.05, one way ANOVA with Sheffe's test).

Conclusions :
CML is present in surgically peeled ILMs and its levels are associated with a medical history of diabetes and the presence of proliferative diabetic retinal changes.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.